The invention concerns a variable dashpot for motor vehicles. It comprises a vibration-suppressing piston-and-cylinder mechanism. The vibration-suppression cylinder contains displacement fluid. The piston divides the cylinder into two displacement compartments. The piston has a piston rod attached to it. The piston is provided with pressure-dependent valves that vary the level of vibration suppression.
Such a variable dashpot is known from German OS 3 434 877. It has a bypass valve that parallels the cylinder. The bypass valve has two components. The first is an axially moving variable valve body that operates in conjunction with an outlet. The second component is at least one pressure-sensitive, spring-loaded valve downstream of the valve body. This dashpot has a serious drawback however. The bypass valve can provide only two vibration-suppression characteristic curves in either the vacuum stage or the compression stage.
A two-tube dashpot with a four-stage level of vibration suppression is disclosed in German Patent 3 631 714 C2.
One variable bypass valve between the two displacement compartments generates two vibration-suppression curves in either the vacuum or the compression stage. Another bypass valve between the lower displacement compartment and an equalization compartment allows four different ways of setting the level of vibration suppression. This dashpot also has drawbacks. First, it has a very long inactive stroke section, especially when both valves are positioned inside it. Second, it is complicated and has many components.